This paper compares cross-laminated timber (CLT) flooring and concrete slab flooring with respect to structural design, cost analysis, and greenhouse gas emissions. The effect of floor span on design values, costs, and carbondioxide emissions is analysed in terms of structural design, economy, and environmental impact. Different crosssections are chosen for this purpose. The study shows that CLT flooring has significantly lower emissions ofclimate-impact greenhouse gases, and its ability to store carbon is significantly greater than the capacity of concrete storage. From an economic point of view, the CLT material is more expensive than concrete. However, the estimated “ready-to-assemble” cost of both floor types is quite similar. The study shows that CLT flooring can compete with a concrete slab floor when it comes to a span as wide as 7m without violating the structural requirements. However, with an increase in span, it is more difficult to meet the requirements for vibration for aCLT floor than for a concrete slab. At shorter spans, the moment capacity is often a decisive factor for concrete slabs while deformation is the decisive factor for a CLT floor. For larger spans, resonance frequency and deformation are crucial for the CLT floor, while the long-term deformation of the concrete is the decisive factor in structural design.